1. Field of the Invention
The present invention relates generally to apparatus for injecting fluids and, more particularly, to apparatus for injecting micro-volumes of fluid.
2. Description of Relevant Art
Injectors for accurately delivering minute quantities of fluids are known in the art. Such injectors may include a piezoelectric valve for precisely and controllably delivering the fluid from a fluid supply to the injector outlet via an inert gas environment.
Prior art piezoelectric valves include a piezoelectric member which typically is spring-biased or loaded so as to position an orifice seal (which is carried by the piezoelectric member) against the outlet orifice of the valve. The piezoelectric member serves as the drive which operates the valve to inject the fluid. Upon the application of electrical current, the piezoelectric member and attached seal move away from the orifice which permits fluid to exit the valve outlet orifice.
A major drawback of conventional piezoelectric valves is that the operational components thereof are contained in a completely enclosed housing and, consequently, cannot easily be accessed. This creates problems because such conventional valves often require adjustment or servicing of some type. In short, prior art piezoelectric valves do not permit sufficient access to the internal components. Moreover, the piezoelectric member is disposed within the fluid pathway, i.e., the fluid directly contacts the piezoelectric member. This may have possible adverse effects on the piezoelectric member and limit the operational life thereof. In view of this, the selection of suitable piezoelectric members also may be limited.
In addition, conventional piezoelectric valves typically must be pressurized to operate and, further, have a limited range of operation, i.e., the volumes of fluid the valves are capable of injecting are limited. Further, known piezoelectric valves are somewhat bulky which limits the number of applications in which the valves may be used. Stated otherwise, such conventional valves cannot be used in injector assemblies having minimal space for disposition of the piezoelectric valve.
Accordingly, there is a need in the art for a piezoelectric valve that is capable of injecting micro-volumes of fluid in a very precise and controlled manner, provides easy access to the internal components of the valve for servicing, replacement, etc., can be used with a wide range of fluids, e.g., either non-caustic chemicals or caustic chemicals, and has a minimal overall size to permit use in reduced size applications.